Don't be
surprised if you see some coverage soon about a new study claiming that
fine particulate matter (PM2.5) could be killing thousands of
Californians every year. The study will likely be touted as
"confirmation" of previous work that first made PM2.5 a health scare in
the early 1990s. Don't be further surprised if this new study is
then used by the California Air Resources Board (CARB) to gin up more
regulations that will make it harder to drive a diesel truck or run
most businesses in this state. That's how it works: A study says
we're all gonna die and CARB rides in to slay whatever dragon a handful
of scientists claim to see. Before you get all puffed up, I'm not
some kind of air pollution advocate. Our approach to cleaning the
air must be reasonable, however. And that's where I say we've gone off
the rails, chasing ever smaller returns at an ever greater cost.
I think a close examination of the science bears me out. Right
now, we're in a period when the public can read and comment on the new
study. But that rarely happens. Yet it's a crucial moment. It's
when scientists claim there is an identifiable link between air
pollution and premature deaths. That link is called the hazard
ratio. The hazard ratio is then used to come up with an actual
number of human beings who -- supposedly -- will be felled by too many
whiffs of PM2.5. The costs of those deaths are then weighed against
regulatory costs. That ratio then justifies the rules. For
example, in 2006, CARB said diesel PM2.5 and ozone from ports and goods
movement caused 2,400 premature deaths a year (see box for more info on
death estimates) at a cost of $19 billion. They proposed a host of
rules -- at an annual cost of between $200 million and $300 million --
to cut emissions. So, for every $1 invested toward reducing pollution,
there would be $3 to $8 in benefits from avoided health costs, mostly
from premature deaths, CARB said. This new California-specific
study, by Michael Jerrett, C. Arden Pope and a group of other
like-minded air pollution scientists, pegs the hazard ratio for all
causes of premature deaths at 1.08. Which means that exposure to
PM2.5 (at concentrations of 10 micrograms per cubic meter) elevates our
risk of dying prematurely by 8 percent -- maybe. The authors
called that significant, and it could be. But, oh those devilish
details, how they can change the balance. Jerrett and Pope looked
at PM2.5 and premature deaths under eight other models, each of which
came back with zero effect of premature death. Only one model
showed any effect worth noting. It was a model no one had used before
called "conurbation" in which California was carved into five big
pieces. Jerrett told me he had to create these conurbations to
make up for the fact that death rates overall are far lower in urban
areas like Los Angeles than in rural areas like Kern County. OK,
so they have one model out of nine that shows any kind of effect.
A deeper look, however, shows the range of uncertainty for even that
model hits the zero mark. As in, PM2.5 isn't putting anyone six feet
under before their time. Another weakness: they used data from
1982 to 2000. Our air quality has improved vastly since the 1980s, or
even the 1990s. Two other recent California studies (Zeger, 2008
and Lipsett, 2011) both using more up-to-date data from 2000-2005 show
no effect of premature death from PM2.5. I say the Jerrett's and
Pope's conclusion of a "significant" effect is a pretty big reach,
especially considering how costly CARB regulations can be -- expensive
filtration devices and requirements that operators phase out entire
engine models by buying whole new fleets, etc. Since this
conurbation model is so new (Jerrett didn't even list it in his
methodology outline when he got funding for the study from CARB) and
the effect seems so slight, I wondered if the authors would recommend
further study before CARB uses the study to craft new policies.
Nope. His model is "state of the art" and represents the "best
estimates available" of premature deaths from PM2.5 exposure, Jerrett
said. Pope was more circumspect saying public policy is a
judgement call and his work is just focused on the science. Yeah,
but science is the foundation for regulations. Well, some science
anyway. CARB has routinely ignored other studies that show no
effect of premature death from PM2.5. Now they've put out numbers that
suggest the new rules will lead to 291 fewer deaths a year? I
don't see it. Opinions expressed in this column are those of Lois
Henry, not The Bakersfield Californian. Her column appears Wednesdays
and Sundays. Comment at http://www.bakersfield.com, call her at
395-7373 or e-mail lhenry@bakersfield.com